This invention relates to an innovative flume for use in sewers to improve the utilization of the sewage collection and conveyance networks as temporary storage units in order to either reduce diurnal peak flow rates at a downstream bottleneck or a wastewater treatment plant (WWTP) or to shift the time period when the peak flow reaches the WWTP.
In the wastewater collection and treatment industry, flumes are well known devices for use as flow measurement devices for open channel flow. A variety of prior-art flumes are available for this use. Specific examples include the Palmer-Bowlus, Parshall, Trapezoidal, Cutthroat and H-flumes. The flow rate for a given flume is a function of the head-loss through the flume. Some flumes, such as a Parshall flume, are designed so that the flow rate through the flume is determined solely as a function of the water height upstream of the flume. Flumes are not used to regulate flow but rather are designed so that the expected range of flows can be accommodated without interfering with the flow rate. Flumes are designed to passively measure all flows within their design range and to minimize altering the fluid flow rate.
Wastewater treatment plants are typically designed and built to treat a fluctuating flow stream, one that varies widely throughout the day and possibly the season in both quantity and strength. Routine flow variations typically occur in a daily cyclical fashion, with flow rates becoming higher than average during the day and lower than average at night. Sometimes the daily flows exhibit a bimodal peak flow with a first peak in the morning and a second peak during the evening. Some sewer systems are also impacted by precipitation events during which rainfall or snowmelt may enter the sewer system through various entry points. These events will also produce peak flow rates that can be significantly higher than the typical diurnal fluctuation. The precipitation related flows also tend to be relatively infrequent due to the generally intermittent nature of precipitation. These variations in flow require process units and equipment to be large enough to meet reasonable daily peak loadings, periodic seasonal peak loadings such as rain events, and the projected demand imposed by future growth. Smoothing the flow at a more even rate results in loadings being more consistent, and biological and energy demands being more stable. Through the dampening effects of equalization, only the treatment units and equipment needed to meet the equalized flows have to be operated. One method known to accomplish equalization is the use of equalization basins. Equalization basins have a volume generally less than 35% of the WWTP capacity. They can be located on site or upstream of the WWTP and arranged as separate in-line or off-line tanks. The result is an overall improvement in WWTP efficiencies, more consistent removal rates, reduced electrical peak-demand charges, and possibly decreased power consumption. Additional benefits include the dissipation of shock loads that most WWTPs experience and the extension of the operating capacity within the existing facility because the initial design capacity was oversized to allow for peak demands.
The use of existing sewer capacity to reduce daily diurnal flows has been described in U.S. Pat. No. 6,318,395 by Anderson, et al. dated Nov. 20, 2001. The present invention describes an innovative flume to be used to reduce the daily diurnal flow peaks.
This invention relates to an innovative flume for use in sewers to optimize the utilization of the sewage collection and conveyance networks as temporary storage units in order to either reduce peak flow rates reaching a downstream bottleneck area of the sewer system or a wastewater treatment plant (WWTP) and to shift the time period when the peak flow reaches the WWTP to improve performance and reduce costs.
This invention provides a simple, safe and effective flume for controlling wastewater flow rates. A benefit of controlling wastewater flow rates by lowering peak flows to a sewer system and a WWTP, capital expansions can be delayed. Additionally, at a WWTP, lower peak flows result is an overall improvement in WWTP efficiencies, more consistent removal rates, reduced peak-demand charges, and decreased power cost.
There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are additional features of the invention that will be described hereinafter and which will form the subject matter of the claims appended hereto.
It is therefore an object of the present invention to provide a new flume to control peak flow rates and thereby improve the performance and reduce the cost of sewage conveyance and treatment. This new method and apparatus has many of the advantages mentioned heretofore and several novel features that result in a new method and apparatus which is not anticipated, rendered obvious, suggested, or even implied by any of the prior art methods to improve the performance and reduce the cost of sewage conveyance and treatment, either alone or in any combination thereof.
Still yet another object of the present invention is to provide a new flume that will use the sewage collection and conveyance networks as temporary storage units in order to control flows resulting in reduced peak flows.
It is another object of the present invention to provide a new flume to reduce peak flow rates or provide flow equalization that can be easily networked throughout a sewer system as needed.
It is another object of the present invention to provide a new method to reduce peak flow rates or provide flow equalization that can be easily configured to meet the individualized requirements of a particular sewer system and the downstream WWTP.
It is another object of the present invention to provide a new flume that allows minimum flow rates in sewers to be maintained upstream and downstream of the flume
It is another object of the present invention to provide a new flume that does not interfere with low flows for a sewer.
It is another object of the present invention to provide a new flume that includes overflow features for flows above the flumes capacity.
It is another object of the present invention to provide a new flume that minimizes clogging.
It is another object of the present invention to provide a new flume to reduce peak flow rates or provide flow equalization that can be easily automated.
It is another object of the present invention to provide a new flume to reduce peak flow rates or provide flow equalization that is rugged and reliable.
It is another object of the present invention to provide a new flume to reduce peak flow rates or provide flow equalization which may be easily and efficiently manufactured and marketed.
It is another object of the present invention to control flow rates to a WWTP in a way that lowers the electrical costs for a WWTP.
An even further object of the present invention is to provide a new method to reduce peak flow rates or provide flow equalization which is susceptible of a low cost of manufacture with regard to both materials and labor.
It is another object of the present invention to provide a new flume that is compatible with existing sewer cleaning technology.
The flume must be durable and corrosion resistant. Materials of construction for prior-art flumes in sewer systems would also be appropriate for this invention. Flumes are often made of metals such as aluminum or stainless steel, various plastics, wood, fiberglass or concrete. Materials that are susceptible to corrosion such as iron or steel can also be used if protected with a suitable corrosion resistant coating such as coal tar epoxy paint.
The flume may be constructed out of concrete which could be placed in a removable form or poured into a form that would become an integral part of the flume.
The flume could be provided with attachment points for easy installation.
These together with other objects of the invention, along with the various features of novelty which characterize the invention, are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and the specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated preferred embodiments of the invention.